1. Field of the Invention
The present invention relates generally to medical devices, and more particularly, to securing an implanted medical device in a patient.
2. Related Art
Hearing loss is generally of two types, namely conductive and sensorineural. The treatment of both types of hearing loss has been quite different, relying on different principles to enable sound percepts to be generated in a recipient's brain. Conductive hearing loss occurs when the normal mechanical pathways for sound to reach the hair cells in the cochlea are impeded, for example, by damage to the ossicles. In such cases, hearing is often improved with the use of conventional hearing aids. Such hearing aids amplify sound so that acoustic information reaches the hair cells of the cochlea. Typically, conventional hearing aids utilize acoustic mechanical stimulation, whereby the sound is amplified according to a number of varying techniques, and delivered to the inner ear as mechanical energy. This may be, for example, through a column of air to the eardrum, or through direct delivery to the ossicles of the middle ear.
Sensorineural hearing loss is due to the absence or destruction of the cochlear hair cells which are needed to transduce acoustic signals into auditory nerve impulses. Individuals suffering from this type of hearing loss are unable to derive any benefit from conventional hearing aids regardless of the magnitude of the acoustic mechanical stimulus. In such cases, cochlear™ implants (also referred to as cochlear™ devices, cochlear™ prostheses, cochlear™ implant systems, and the like; simply “cochlear implants” herein) have been developed to provide hearing percepts to such individuals. Cochlear implants provide electrical stimulation via stimulating electrodes positioned as close as possible to the nerve endings of the auditory nerve, essentially bypassing the cochlear hair cells. The application of a stimulation pattern to the nerve endings causes impulses to be sent to the brain via the auditory nerve, resulting in the brain perceiving the impulses as sound.
It is relatively common for some hearing impaired individuals to experience profound hearing loss for high frequency sounds, and yet still be able to discern middle-to-low frequency sounds. Traditionally, such individuals typically do not receive a cochlear implant, as noted above, due to the potential trauma caused by the implantation of a traditional electrode assembly into the cochlea. Rather, in the majority of such cases, such an individual receives treatment to preserve and improve hearing in the middle-to-low frequency range, typically via a conventional hearing aid. Minimal effort would be expended to restore hearing in the high frequency range. Unfortunately, such individuals generally experience poor restoration of their hearing with conventional hearing aids alone.
Recently, there has been an increased interest in assisting individuals with residual hearing who do not experience adequate restoration from conventional hearing aids alone. One proposed approach for assisting these individuals is through the use of Electro-Acoustical Stimulation (EAS). So called EAS devices provide electrical stimulation of the cochlea in conjunction with acoustical stimulation.